Soft inplane helicopter rotor mountings have been heretofore known. A representative system is shown in U.S. Pat. No. 4,257,739 in which elastomeric thrust and elastomeric inboard bearings provide soft inplane operation while accommodating pitch change.
Laminated composite rotary yoke structures have also been known. A representative system is shown in U.S. Pat. No. 4,293,276 wherein a composite laminated rotary yoke provides for a bearingless type of installation.
U.S. Pat. No. 4,306,837 discloses a bearingless tail rotor structure for helicopters wherein flex sections for feathering purposes are provided through a fiber-reinforced composite tension-bearing strap extending span-wise.